1. Field of the Invention
The present invention relates to a digital image processing apparatus and a method for the same, in particular to a digital image processing apparatus capable of providing increased image sharpness with reduced noises, and a method for the same.
2. Description of the Related Art
Typically, the quality of an image shown by a display apparatus may be improved by adjusting its contrast, brightness, hue or sharpness.
The sharpness of an image is decided by the clearness of the boundary between bright and dark areas. In most cases, the boundary between bright and dark areas is the high-frequency part of video signals. If, during processing sensed video signals, the high-frequency part of the video signals is somewhat lost or distorted, the resulted display image would be blurred and illegible at the boundary between bright and dark areas.
A typical method for sharpening an image is edge enhancement. The method uses Laplacian or Sobel high-pass filter to detect edges of an image, and to enhance the detected edges. Relevant hardware implementations for edge detection and enhancement operations have been proposed, such as U.S. Pat. No. 6,404,460 an U.S. Pat. No. 6,441,866.
However, because both noises and the boundary between bright and dark areas belong to high-frequency domain, the high-pass filtering in the conventional image edge enhancement method increases both the sharpness and the noises in an image, if information at the edges of an image is not taken into particular consideration.